The present invention relates to switching circuit, and more particularly, to a switching circuit implemented by a medium- or low-voltage transistor instead of a high-voltage transistor and a direct-current-to-direct-current (DC-DC) converter including the switching circuit.
Display devices or portable electronic devices usually use a DC-DC converter, which increases or decreases a constant DC voltage provided from the outside, in order to provide operating power necessary to operate internal elements.
The DC-DC converter usually includes a charge pump including a capacitor and a switch. The switch is implemented using a transistor. It may be implemented using a high-voltage transistor or a low-voltage transistor depending on the level of voltage to be switched. Since the high-voltage transistor requires a high withstanding voltage as compared to the low-voltage transistor, it has a thicker gate insulating layer and a longer channel than the low-voltage transistor. That is, the high-voltage transistor is much larger than the low-voltage transistor, and therefore, the more high-voltage transistors are used, the more area is needed.